The present invention is directed to intraocular lenses (IOLs). More particularly, the invention relates to IOLs which are adapted to provide accommodating movement in the eye.
The human eye includes an anterior chamber between the cornea and iris, a posterior chamber, defined by a capsular bag, containing a crystalline lens, a ciliary muscle, a vitreous chamber behind the lens containing the vitreous humor, and a retina at the rear of this chamber. The human eye has a natural accommodation ability. The contraction and relaxation of the ciliary muscle provides the eye with near and distant vision, respectively. This ciliary muscle action shapes the natural crystalline lens to the appropriate optical configuration for focusing light rays entering the eye on the retina.
After the natural crystalline lens is removed, for example, because of cataract or other condition, a conventional, monofocal IOL can be placed in the posterior chamber. Such a conventional IOL has very limited, if any, accommodating ability. However, the wearer of such an IOL continues to require the ability to view both near and far (distant) objects. Corrective spectacles may be employed as a useful solution. Recently, multifocal IOLs without accommodating movement have been used to provide near/far vision correction.
Attempts have been made to provide IOLs with accommodating movement along the optical axis of the eye as an alternative to shape changing. Examples of such attempts are set forth in Levy U.S. Pat. No. 4,409,691 and several patents to Cumming, including U.S. Pat. Nos. 5,674,282 and 5,496,366. The disclosure of each of these patents is incorporated herein by reference. These lenses are biased to be located in the posterior-most position in the eye under rest or resting conditions. When near focus is desired, the ciliary muscle contracts and the lens moves forwardly (positive accommodation). In the absence of ciliary muscle contraction, the lens moves rearwardly to its posterior-most resting position. Because of this posterior bias and the configuration of the lens, the posterior wall of the capsular bag is subjected to a substantial degree of stretching when the lens is in the posterior-most position. One problem that exists with such IOLs is that they often cannot move sufficiently to obtain the desired accommodation.
It would be advantageous to provide IOLs adapted for accommodating movement which can achieve an acceptable amount of accommodation with reduced risk of damaging the capsular bag.
New accommodating IOLs have been discovered. The present accommodating IOLs take advantage of the ability of the eye to move the present IOLs sufficiently, for example, as a result of zonular tension acting on the capsular bag of the eye. The present IOLs effectively reduce detrimental stretching of the capsular bag even with the lens in the posterior-most position in the eye. Moreover, the present IOLs allow the capsular bag to retain sufficient elasticity to change its diameter, in particular its equatorial diameter, sufficiently to provide the desired degree of accommodation. In addition, the present lenses preferably are configured to advantageously increase the amount of accommodating movement achieved as a result of elasticity of the capsular bag and the action of the ciliary muscle. The present IOLs are straightforward in construction, can be implanted or inserted into the eye using systems and procedures which are well known in the art and function effectively with little or no additional treatments or medications being required.
In general, the present IOLs comprise an optic adapted to focus light toward a retina of an eye; and a movement assembly coupled to the optic and adapted to cooperate with the eye to effect accommodating movement of the optic. The movement assembly preferably circumscribes, more preferably substantially completely circumscribes, the optic and comprises a member including a proximal end portion coupled to the optic and a distal end portion extending away from the optic and adapted to contact the capsular bag of the eye. The movement assembly circumscribing the optic very effectively enhances the degree to which the elasticity of the capsular bag and the action of the ciliary muscle acting on the zonules and the capsular bag causes accommodating movement of the optic. Preferably, the movement assembly is adapted to cooperate with the eye to effect accommodating movement of the optic upon radial, for example, diametrical, compression by the capsular bag of the eye.
In a very useful embodiment, the optic has a far vision correction power, more preferably a far vision correction power for infinity, in the unaccommodated state. Thus, with the IOL located in the posterior-most position, distant objects can be easily and accurately viewed.
Preferably, the movement assembly is positioned relative to the optic so that, with the IOL at rest, for example, in the eye, the optic vaults anteriorly of the distal end region of the movement assembly. This anterior vaulting feature reduces the risk of detrimental posterior stretching of the capsular bag with the IOL located in the posterior-most position in the eye. Thus, in this posterior-most position, the optic of the IOL may contact the capsular bag but, because of the anterior vaulting, causes a reduced amount of posterior stretching of the capsular bag relative to a similar IOL without the anterior vaulting feature located in the posterior-most position. The anterior vaulting feature, in addition, is effective in at least assisting in increased amounts of accommodating movement, again relative to a similar IOL without such anterior vaulting feature.
The present IOLs preferably are sized to fit the capsular bag of the eye in the unaccommodated state substantially without stretching the capsular bag. Proper sizing of the IOL facilitates enhanced accommodating movement of the IOL in the eye.
Because of the size and configuration of the present IOLs, such IOLs preferably provide an amount of axial movement anteriorly in the eye in the range of about 0.5 or about 1.5 mm to about 2.0 mm with about 1.0 mm of reduction in the equatorial diameter of the capsular bag.
In one very useful embodiment, the optic of the IOL has a diameter in the range of about 3.5 mm to about 7 mm, more preferably about 5 mm to about 6 mm. The overall diameter of the present IOLs preferably is in the range of about 8 mm to about 11 mm or about 12 mm.
The movement assembly may be adapted to be affixed to the capsular bag of the eye including the IOL.
The movement assembly preferably is sufficiently flexible to facilitate movement of the optic relative to the distal end region of the movement assembly being acted upon by the eye. The movement assembly may include a hinge assembly positioned proximally of the distal end region of the movement assembly. Such hinge assembly is effective in facilitating the accommodating movement of the optic in the eye. The hinge assembly may include one or more regions of reduced thickness, for example, circumscribing the optic. These reduced thickness regions are effective to provide a desired degree of flexibility to the movement assembly. The movement assembly may have a minimum thickness at the proximal end region and a maximum thickness at the distal end region. In one embodiment, the movement assembly includes no hole or holes passing through, for example, axially through, the movement assembly.
In a very useful embodiment, the distal end region of the movement assembly includes a peripheral edge configured to inhibit cell growth from the eye in front of or in back of the intraocular lens. In a particularly useful embodiment, the movement assembly has an anterior face and an opposing posterior face with the peripheral edge being between these two faces. The intersection of the peripheral edge and at least one of the anterior face and the posterior face forms a peripheral corner located at a discontinuity between the peripheral edge and the intersecting face. Cell growth from the eye in front of or in back of the movement assembly preferably is more inhibited relative to a substantially identical intraocular lens without the peripheral corner.
In a further broad aspect of the present invention, methods for inserting an IOL in an eye are provided. Such methods comprise providing an IOL in accordance with the present invention, as described herein. The IOL is placed into the eye, for example, in the capsular bag of the eye, using equipment and techniques which are conventional and well known in the art. The IOL is placed in the unaccommodated position in the eye. In one embodiment, the placing step is effective so that the optic of the IOL is radially, e.g., diametrically, compressed by the capsular bag, for example, by the elasticity of the capsular bag, of the eye to effect accommodating movement of the optic of the IOL. No treatments or medications, for example, to paralyze the ciliary muscle to facilitate fibrosis or otherwise influence the position of the IOL in the eye, are required. Preferably, the optic is deformed prior to being placed into the eye. Once the IOL is placed in the eye, and after a normal period of recovery from the surgical procedure, the IOL, in cooperation with the eye, provides the mammal or human wearing the IOL with near focus accommodation. In the unaccommodated state, the IOL provides the mammal or human wearing the IOL with far vision correction.
Any and all features described herein and combinations of such features are included within the scope of the present invention provided that the features of any such combination are not mutually inconsistent.
Additional aspects and advantages of the present invention are set forth in the following description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.